Just succeeded in making a cheap Chinese Power meter wireless using ESP-07 and MQTT.
Below picture is the test setup.

IMAG0032_1.jpg

The output on my ESP device topic looks like
/Domoticz/MQTT/Device ESP_009D5CDF,247.3,17.7
/Domoticz/MQTT/Device ESP_00A1B476,1
/Domoticz/MQTT/Device ESP_009D5CDF,247.3,17.7
/Domoticz/MQTT/Device ESP_009E69A1,1
/Domoticz/MQTT/Device ESP_009E6AC0,1
The one with a single digit are MQTT switches (1 = off, 0 = on)
The dual digit one is the MQTT power meter Volt/Watt which updates every second for now

PS: Voltage looks high but that is due to the 1:1 safety transformer I used during testing.
The PowerMeter PSU is not suitable to drive the ESP and is directly connected to the mains so I will add a cheap $2 PSU in there too.

I was also busy doing that (i am the 'Frank' from the reactions on the first article) and had it even working in Domoticz (Arduino reading the meter, ESP8266 transmitting the values to virtual sensors in Domoticz). But like you said: the powersupply in the wattmeter isn't capable enough of powering all those 'parasite' modules that you/we connected. So therefore i never finished it. I was also thinking about popping in a cheap power supply, but after reading this, i don't trust these cheapo chargers from China for a single bit. Really dangerous designs being made there

Can you share your code? Maybe i will pick it up when i am bored and have some spare time

P.S. Be careful when testing, the author of those articles alerted that the datalines could carry 230V! When i was fiddling with the wattmeter being powered, i had it powered through an UPS running on batteries. Otherwise you could fry your PC because 230V could be blasted through your USB-port. Or is the 'MURR' device in your picture a isolation transformer?

Yes, this is based on the articles you mentioned, but now with ESP only, so no Arduino in between the meter and the ESP. The ESP is sending MQTT data directly to my broker. From there I pick it up using NodeRed and do what I want it to do.

I'm still in the prototype phase, just ordered the first PCB v1.0. Also need to figure out how to use JSON with the ESP instead of CSV separated values. If you send me a PM, i will share the first info with you.

JP1 connects to separate 5V PSU
JP2 connects to meter (CLOCK, MISO, MOSI, GND)
JP3 used to load new software (disconnect meter, hook up serial port with 5V to power the ESP (through 3.3 v regulator.
The rest of the components is to level shift 5v -> 3.3v and buffer the ESP from the outside.

Whoooo, hold your horses (I see you like riding them). It's not my fault you don't understand how this works. First off all start reading about MQTT (Google is your friend), build your own MQTT broker like mosquitto (already on the SD image for RPI) and play with the mosquitto_pub/sub commands. Then come back with questions, maybe I can help you.

Sine wrote:Since you join the ground of your board and the ground of the meter ... I would not touch that nice shiny and very conductive WiFi connector

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Yes you are right, the ESP-7 internal antenna is not so good, so I used an external one on my prototype. My other meters use the ESP-12(E) this has a better anntena so I could remove the external one.